Discharge bar for neutralizing static electricity



I Dec. 20 1927.

v w. H. CHAPMAN DISCHARGE BAR FOR NEUTRALIZING STATIC ELECTRICITY Filed April 8. 1927 FT. [9177M i v 8% NN Rh mm MN QM. v a xww mwh y? y Wm .M. Q w :m w v .HIMWH, n 7 f m *N I n awhla w w 3 M m w .a Q. A si 61 a t a Syn 3 Sn wk .0 Km NM f i N w. .W w xw mww .BQN. V i

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UNITED STATES PATENT OFFICE.

WILLIAM HENRY CHAPMAN, OE PORTLAND, MAINE, ASSIGNOR TO CHAPMAN ELEC- TRIC NEUTRALIZER COMPANY OF PORTLAND, MAINE, OF PORTLAND, MAINE, A

CORPORATION OF MAINE.

DISCHARGE BAR FOR NEUTRALIZING STATIC ELECTRICITY.

Continuation of application Serial No. 127,464, filed August 5, 1926. This application filed April 8, 1887. Serial No. 181,994.

My invention relates to dischar e bars for neutralizing static electricity. ore especially it relates to discharge bars or inductors which are placed near the surface of textile fabrics or paper in the process of manufacture or printing, whereby the static charge in these materials is neutralized by the discharge of high voltage alternatmg charges through the air. ThlS present application is filed as a continuation of application Serial Number 127,464, filed August 5, 1926, and similarly entitled.

An object of the present invention is to provide an improved construction of discharge bar, of the type disclosed in my Letters'Patent No. 940,431 of November 16th 1909, wherein current is supplied through a cable housed within but insulated from a 'grounded metallic tube. About this cable 20 are condenser sleeves each of which is connected with a discharge point projecting.

outside the tube through a longitudinal slot thereof. Certain practical difficulties have been encountered in the use of the use of the bar illustrated in my said patent which it is the purpose of the present invention. to eliminate. Among these is the blunting of the discharge oints due in part to the wearing action of t e emanating mm and in part to the cleaning operations "necessary to rid the points of collected dirt orlint in order that their effectiveness may be unimpaired. It has also been found necessary from time'to time to remove from the interior of the tube the dirt and-lint which enters through the slot; and as such removal requires the disassembling of the bar and subsequent-reassembling and installation, time and labor are expended and production lost while the 40 machine on which the bar is placed is idle. In the bar of the aforesaid patent it has also been necessary to guard against the possible slippage of the condenser sleeves along the cable as the latter becomes old and dried and somewhat smaller in diameter. The

danger of these sleeves coming into conducting communication with "one another is. a serious menace where the discharge bar is used in the presence of inflammable vapors such as occur in the manufacture of rubber coated fabrics and the like. Another serious objection to the bar of the patent is the,l1ability of breakage of the protruding ends of the insulating blocks that encircle the sleeve and house the discharge point. It is, of course, obvious that the bar must be within operating range of the paper or fabric passing by it, but in many machines the space available for the bar is so limited, because of the presence of delivery tapes, fly sticks and other moving parts, that when the bar of the patent is installed the projecting ends of the blocks are necessarily closer than would be desired if more space were available. In consequence these blocks have served to catch upturned edges of paper or other material being neutralized and cause a jam to occur which, before the machine could be stopped, fre uently resulted in a splitting of the block eginning usually in the slot engaged by the metallic tube. If one edge of this block is broken away, destroying the slot formation on its side and freeing it from the tube, the discharge I oint may be brought near enough to the tu e to permit the current to jump thereto by spark discharge, or the block may tilt and rest I against the inside of the tube resulting in a loss of the charge by leakage through this surface contact.

It is an object of the present invention to provide an improved insulating block for the condenser sleeves and the discharge points which will act as positive spacers to prevent the sleeves from coming into contact with one another and which will also serve collectively to close the slot opening in the outside tube. It is a feature that the insulation blocks are so shaped that they are properly supported by limi d contact with the inside surface of the tube, serve to support the cable centrally therein, and project I .just into the slot of the tube without'projecting beyond it. Another object is to provide discharge points which are not affected either-b such cleaning as is necessary or by the disc arging ions These objects and the features which characterize the improved construction herein disclosed are attained by providing an insulating block having bearing surfaces of limited extent adapted to rest against the inner surface of the cylindrical tube to retain the block in position.' The bottom portion of the block projects into a longitudinal slot of the tube, and is of such width that when the tube is filled with the blocks and the bottom portions are in end contact with one another, they completely fill the slot and prevent entrance of dirt or lint to the tube. A hole in the body of the block receives the metallic sleeve which serves as the condenser; This body portion is shorter than the bottom or- 'legs extending through suitable openings provided in the bottom portion of the block. By choosing a wire of sufficiently small diameter, it is immaterial as regards its effectiveness as a discharge oint, whether its end is sharpened or not. onsequently the ends are preferably left unsharpened, and it follows that thereafter the cleaning of the ends or the wearing action due to the discharge does not injuriously affect the points. The legs of the U-shaped wire near this base are crinkled to engage the sides of the hole through which the legs extend so that the points will be maintained centrall thereof.

It is intended that the patent s all cover by suitable expression in the appended claims, whatever features of patentable novelty-exist in the invention disclosed. In the accompanying drawings:

Figure 1 is an elevation of a discharge bar embodying the present invention, showing its relation to the material being-neutralized, and with its electrical connections illustrated somewhat diagrammaticall Figure 2 is a plan of the discharge bar with a portion of the tube cut away to show the insulating blocks;

Figure 3 is an elevation in section on line 3-3 of Figure 2, but with some of the condenser blocks in full view; and

Figure 4 is an elevation somewhat enlarged, of a section taken transversely of the bar as on line 4.--4 of Figure 3.

Referring to the drawings, the improved discharge bar comprises a metallic tube 10, which fits upon an insulating terminal block 12 and is held thereto by a strap 14 and screws 16. A cable 18, having a eavy insulated covering 18', is secured within a socket 12 in the terminal block 12, by a metallic block 20. to which the wire 18" is preferably soldered. A pin 22, which threads into the cable block 20 and contacts with the wire 18, is clamped to the terminal block 12 by binding nut 24 and is adapted to be connected with a lead 26 from a source of high tension alternating current. The cable 18 extends through the hollow of the tube 10 into a socket provided in an insulating plug 28 which closes the'end of the tube. Intermediate the terminal block 12 and the plug 28 are several condensers in the form of metallic sleeves 30 slidably fitting about the in'ulating covering 18. Preferably these sleevesare made of aluminum because of its abilit other suitable metals could be employed if desired. Each sleeve extends through a cylindrical hole in the bod portion 32* of an insulating block 32. T iese blocks can be made of any insulating material although I prefer to use porcelain because most other moulded insulating material is subject to carbonization. Each block has a bottom portion 32 which is somewhat narrower than the main or body portion 32! through which the sleeve 30 extends, although longer in extent so that the 811(1"; of the bottom portions lie outside and beyond the headed ends of the sleeve. This results in the sleeves being maintained in separated relation when their blocks are placed adjacent to one another endwise. Sections 32 at both ends of the blocks extend upwards and downward from the main body portion to form bearing surfaces 32 of limited extent which rest agaiIr-t the inside surface of the tube, there being thus four such bearing surface: at each end of the block. It is important that the surfaces of the blocks in contact with the tube wall be limited in extent as otherwise, with too large a surface contact, the charge will be dissipated through the block to the tube and thus render the bar ineffective as a neutralizer. On the upper side of the block, between the extended sections 32, a slot opening 32 to the sleeve hole is provided and opposite this slot on the underside of the hole wall is a corresponding groove 32 connecting two smaller holes 32 extending downward through the bottom portion 32". Before the sleeve is'placed inthe main hole, a U-shaped wire 34 is passed through the upper slot and main hole until its base 34" rests in the groove 32 and its depending legs 34 extend through the smaller holes 32 Each'leg is crinkled near its junction with the base portion and these crinkles 34 are so proportioned with respect to the site of the holes that when the leg is passed through, the turns of the crinkles engage the hole and centralize the depending straight part of the leg in the hole opening. Preferably the latter is countersunk to make a flaring opening 32 as seen clearly in Figure 4. The wire 34 is slightly thicker than the depth of the groove32 so that when the metallic sleeve 30 is passed through the main hole, it will make good contact with the base of the U-shaped wirea I have found by practical experiencethat to resist corrosion but a wire as fine as .016 inch diameter, or finer, and of a length as much as thirty times its diameter is just as efiicient a discharger whether it is sharpened at the end or not.

The discharge points of my new bar are constructed to meet'this naturally imposed condition andan advantage is thereby secured over the construction shown in Patent No. 940,431 in which long experience has shown that the blunting of the discharge tion ofthe discharge current or of cleaning because the cross section of the metal constituting the point is uniform throughout its length and small enough to be effective at if \vhetever length it is likely to be reduced by wear.

There is a longitudinal slot on the underside of the tube 10 which is just wide enough to accommodate the bottom portions 32 of the blocks' Accordingly when the sleeves and blocks are inserted in the plug end of the tube (prior to the plug being fastened thereto) and the cable is passed through the sleeve, the bottom portions slide along the tubeslot with the bearing surfaces 32 of the blocks restin on the tubes inner wall. It is intended that a suflicient number of such blocks will be inserted in the tube so that when placed in end contact their bottom portions will completely fill the slot 10 in the tube. If for any reason this does not result, short pieces 36 of fibre tubing may be fitted into one or both ends of the tube to hold the blocks in contact and cover any part of the slot opening not filled by the bottom portions of the block. It is not necessary that the portions 32' extend outside ofv the tube 10 in fact, where the space in which the bar is positioned is restricted, it is de sirable to have the portions 32" just flush with the outside surface of the tube 10 as shown in the drawings- In operation my improved discharge bar is located with its active points 34" near to the surface of the paper or fabric 38 to be treated. Connection is made from a source of high voltage alternating current of about 10,000 volts through the lead 26 and bayonet socket 26' to the. terminal pin 22. The high voltage charge'is thus communicated to the cable 18. The wire 18" in this cable constitutes the inside electrode of a condenser, the covering 18' of the cable is the dielectric and each one of the aluminumsleeves isan outside electrode of the condenser and has an alternating charge induced in it of a voltage practically the same as that inthe cable, but of such a very limited quantity that its dischar e will not set fire to the most infiammab e vapors, although of suflicient quantity to neutralize all the charge that can exist on an amount of paper or fabric that can be ma e to pass before a single pair of the discharge points 34".

The induced alternating current in the condenser sleeves 30 flows through the wires 34 and is discharged into the air from their points 34". If the paper is negatively charged, as is usual, the positive ions, represented by the small arrows in Figure 1, will pass to the paper and neutralize the negative ions thereof, and the negative 10I1S will -flow to the tube 10 which must be grounded as indicated at 40. Upon the paper becoming neutralized both positive and negative ions flow to the tube and are dissipated through the ground connection.

The blocks 32 because of their bearing "surfaces on the tube hold the cable centrally of the tube 10 and prevent sagging thereof. The bottom portions fill the tube slot and keep out dirt and lint from the interior of the tube and serve also, by engaging the walls of the slot, to prevent the blocks from rotating. Moreover, these portions,

because they are longer than the body portions of .the body, prevent the condenser sleeves from coming into contact or close enough to cause sparks. This is very important where the bar is used in the presence of inflammable vapors. And since the bottoms 32? are merely flush with the tube there is no danger of the paper or other material passing the bar being caught by them and forming'a pile of the material with consequent strain on the block. With this danger avoided, the bar can be placed in a more restricted space than have the bars heretofore used and still function properly without interfering with the passage of the material.

I claim as my invention:

1.- A discharge bar for neutralizing static electricit comprising, in combination, a grounde metallic tube having a longitudinal slot along one side; insulating terminal blocks closing its ends; an insulated cable within said tube extending between; said terminal blocks; a series of insulatin blocks arranged within said tube about'said cable having bearing surfaces of limited extent adapted to rest on the inner wall of said tube and having bottom portions extending into the tube slot; condenser sleeves carried by said blocks in separated "relation to one another about the cable; and a discharge wire for each sleeve having connection therewith and having a discharge point extending through said bottom portion of the block; the said bottom portions being adapted colleetivel toxfill' said'tube slot when placed in en to end contact. 1

2. A. discharge-bar for neutralizing static electricity comprising, in combinatiom; a grounded metallic tube having a longitudinal slot along one side; iifsu'l'ating terminal blocks closing its ends; anvinsulat'ed cable within said tube extending between said terminal blocks; a series ofwondenser sleeves about said cable; a series of insula'ting blocks arranged within said tube, each havinga body portion rigidly encasing a condenser sleeve and having its ends as extending transversely beyond the body portion to form corner supporting surfaces of limited. extent for contact with the inside surface of the tube,.andhaving a bottom portion extending into said'tube slot; and a discharge :wire in each block having connection with said sleeve."- and having discharge .points extending through said bot tom .portions; the saidbottom portionszof zs sald blocks belng longer than said body por from conducting communication when said tion-Lwhereby the said sleeves are restrained blocksareinend'eontact along said tube. 3;' A discharge bar for neutralizing static electricity comprising, ,in combination, .a '3 fgrounde'd metallictube having a longitudi- '.nal' '"'sl0t along" 0ne side; an insulated cable extending :alongj the axis of said tube; an insulating block 'hayingz'at its "lends laterally extendedpbrtions forming bearing surfaces of- '.l ix'nited="extent adapted to. slide alon'gftheinside of saidtube, having a lonand its two end portions crinkled to hold them in. central position in the two lateral openings through which they emerge to out side the surface of the insulating block.

'4. A discharge bar for neutralizing static electricity comprising, in combination, a

grounded metallic tube having a. longitudinal slot along one side thereof; insulating terminal plugs closing itsends; an insulated cable within said tube extending between said terminal plugs; a series of condenser sleeves encircling said cable at spaced intervals therealong; a supporting block of insulated material for each said sleeve having its body portion around the sleeve and having its ends laterally projecting to form bearing surfaces of limited extentfor contactwith the inner wall of said tube for supporting said sleeve and cable centrally therein; each said blockhaving a portion along one slde thereof of greater longitudinal extent than said body. portion and extending into said tube slot, whereby the said slot is closed bysaid side ortions when placed end to end andzwhereby the sleeves are maintained in spaced,- relation to one another; and conducting means leading fi'0m.-said sleeves through said projecting side portions.

WILLIAM HENRY CHAPMAN 

